Patients will commonly seek medical attention for refractory abdominal pain. The many causes of abdominal pain include pathologies of the gastrointestinal, genitourinary, musculoskeletal, and nervous systems. Unfortunately, a large number of patients will develop chronic abdominal pain that is recalcitrant to definitive therapies and nonspecific treatments such as cognitive-behavioral, physical, and pharmacologic therapies. Although spinal cord stimulation is classically used for neuropathic and ischemic conditions, a growing number of reports describe its efficacy in visceral disease. We describe our experience with spinal cord stimulation in two patients with refractory abdominal pain. Although the exact etiology in these complex patients is not defined, it is theorized that visceral hypersensitivity is at least one component. Finally, we will summarize the applicable literature in order to explain a possible mechanism of analgesia in visceral disease.
[Show abstract][Hide abstract] ABSTRACT: Spinal cord stimulation (SCS) is an adjustable, non-destructive procedure which delivers therapeutic doses of electrical current to the spinal cord for the management of neuropathic pain. The most common indications include post-laminectomy ("failed back surgery") syndrome, complex regional pain syndrome (CRPS), ischemic limb pain, and angina. Other reported applications include visceral/abdominal pain, cervical neuritis pain, spinal cord injury pain, post-herpetic neuralgia, and neurogenic thoracic outlet syndrome.
[Show abstract][Hide abstract] ABSTRACT: The reverse link of cdma2000 uses a code-multiplexed pilot signal to allow for near coherent demodulation at the base station receiver. Typical RAKE receivers approximate maximal ratio combining by using a "pilot filter" to derive a combiner weight estimate from the noisy pilot signal. It is possible to improve on this design by exploiting the channel information that is also embedded in the encoded data-bearing signal. We show how the pilot and data-bearing signals may be used to determine, implicitly, "combiner weights", and explicitly, code symbol log likelihood ratios (LLRs). Simulation results on the cdma2000 reverse link demonstrate SNR gains on the order of 0.5 dB with the default pilot-to-traffic ratios. Even larger gains may be achieved by optimizing the pilot-to-traffic ratio appropriately.
Spread Spectrum Techniques and Applications, 2002 IEEE Seventh International Symposium on; 02/2002
[Show abstract][Hide abstract] ABSTRACT: Introduction. Early animal and human evidence existed for a postsynaptic dorsal column (PSDC) pathway for visceral nociception that, when lesioned, decreased pain of terminal illness. There have been recent anecdotal reports in the literature that spinal cord stimulation (SCS) reduces pain of visceral nociception. We present here a review of the literature supporting a hypothesis that SCS might work by modulating information through the spinothalamic tracts (STT) and PSDC. Methods. A review of the relevant literature regarding nociception, nociceptive transmission, visceral sensitization, and the "brain-gut" axis; and SCS was performed as a foundation for this hypothesis. Key words used for this review of databases and nonindexed relevant journals included visceral pain, visceral nociception, visceral hyperalgesia, visceral neuropathic pain, visceral sensitization, "brain-gut" axis, SCS, PSDC pathway, and STTs. Results. An abundance of both clinical and scientific literature suggests the neuropathic and sensitized nature of chronic visceral nociception. There is also evidence that there may be an interaction between the PSDC pathway and lateral spinothalamic tracts (LSTT) that might be operant in the preclinical and anecdotal clinical evidence that SCS ameliorates the pain of visceral nociception. Conclusions. Chronic visceral nociception may be secondary to visceral sensitization and hyperalgesia and can be affected by the spinal cord and brain, the "brain-gut" axis. There is preclinical evidence and clinical anecdotes that this nociceptive information is transmitted in the central nervous system through the PSDC pathway and LSTT and that SCS decreases pain of visceral nociception. It may be that SCS works by modulation of the above pathways.
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